Speed regulator for an internal combustion engine

ABSTRACT

A speed regulator for an internal combustion engine including a control device regulating the control valve for the fuel-air mixture to the engine. The control device is responsive to a voltage differential between a first voltage proportional to the engine speed and a second voltage based on a preset engine speed value, so as to provide for control of the valve. Another aspect lies in the provision of a thermal switch preventing operation of the control device during time when engine is below a minimum operating temperature, while concurrently maintaining the control valve in an engine idling attitude.

United States Patent [191 Durichen [451 May 7,1974

[ SPEED REGULATOR FOR AN INTERNAL COMBUSTION ENGINE [73] AssigneesDeutsche Vergaser Gesellschaft mbH & Co. K.G., Neuss, Germany [22]Filed: Dec. 30, 1971 [21] Appl. No.: 214,231

[30] Foreign Application Priority Data Apr. 27, 1971 Germany 2120510[56] References Cited UNITED STATES PATENTS 3,667,020 5/1972 Senzaki123/102 3,476,205 11/1969 Hato 123/102 3,661,131 5/1972 Croft 123/1023,636,933 l/l972 Ohtani 123/102 Primary Exa minerLaurence M. GoodridgeAssistant ExaminerRonald B. Cox Attorney, Agent, or Firm-Eric l-I.Waters 57] ABSTRACT A speed regulator for an internal combustion engineincluding a control device regulating the control valve for the fuel-airmixture to the engine. The control device is responsive to a voltagedifierential between a first voltage proportional to the engine speedand a second voltage based on a preset engine speed value, so as toprovide for control of the valve. Another aspect lies in the provisionof a thermal switch preventing operation of the control device duringtime when engine is below a minimum operating temperature, whileconcurrently maintaining the control valve in an engine idling attitude.

8 Claims, 2 Drawing Figures SPEED REGULATOR FOR AN INTERNAL COMBUSTIONENGINE BACKGROUND OF THE INVENTION 1. Field of the Invention Thisinvention relates to a speed regulator for an internal combustion enginehaving a control valve for regulating the flow of fuel-air mixture tothe engine and, more particularly, to an improved electrical controldevice connected to the control valve and which is adapted tocontinuously measure the speed of the engine, compared the measuredspeed with a preset speed value, and adjust the mixture flow ratethrough the control valve in response to any differential between themeasured engine speed and preset values.

2. Description of Prior Art Speed regulators for controlling the idlingspeeds of internal combustion engines are widely known. For example,presently used regulators provide for comparisons between the electricalvoltage of a tachometer generator with a second voltage which is setproportionate to a predetermined speed value or constant'for the engine,and which utilize the measured voltage differential between the twovoltages to control an engine air supply or fuel-air mixture supplyvalve.

Prior art regulators are incapable of providing control for maintainingthe engine at a speed which is continuously commensurate with therequired preset speed value. In effecting speed control during theidling operation of the engine, a certain degree of fluctuation orextent of deviation from the preset speed value is permissible andgenerally harmless to the engine.

However, in order to maintain the speed of the internal combustionengine at constant value during the collective operating range of theengine and in view of varying loads, measures are required which arebeyond the reach of the present state of technology.

Speed regulators as presently known are readily disrupted and renderedinoperative. Thus, for example, upon interruption of the power suppliedto the regulator, the internal combustion engine may readily exceed itspermissible speed and be thereby damaged. Furthermore, presently usedregulators provide no protective measures to provide against thestalling of the internal combustion engines in view of premature highspeeds under load upon cold starting.

SUMMARY OF THE INVENTION In accordance with the present invention, theproblems and drawbacks encountered in prior art speed regulators aresolved by providing, in the electrical circuitry of an internalcombustion engine speed control device, a thermal switch which issensitive and responsive to the operating temperature of the internalcombustion engine, the electrical control device being restrained fromacting upon a fuel-air supply control valve ofthe engine until theinternal combustion engine reaches a predetermined minimum operatingtemperature. Furthermore, the control valve, which is positioned in thefuel-air conduit leading to the internal combustion engine, is providedwith a device which automatically sets the control valve into a flowcondition corresponding to the engine idling mode upon interruption ofthe current being supplied to the electrical control device. The thermalswitch may, for example, be

responsive to the cooling system temperature of the internal combustionengine rather than the temperature of the engine itself, and may belocated in the current supply circuit of an actuating motor for thecontrol device, or in a separate electrical circuit.

In a modification of the present invention, the control valve cooperateswith a variable-speed electric motor which is connected, across a lowvoltage relay, with an independent power source, whereas the relay isresponsive to the power or current supply for the control device. Uponinterruption of the current flow to the electric control device, theelectric motor effects positioning of the control valve into theinternal combustion engine idling operational mode.

In another aspect of the invention, the engine speed regulator assemblyincludes an electro-magnetic coupling which is located between theelectrical control device and the control valve, and which provides formechanical separation between these components upon interruption of thecurrent supply tothe electrical control device is interrupted. Thecontrol valve further includes a tension spring which positions andretains the valve in its closed or engine idling mode in response toseparation of the mechanical connection between the control valves andelectrical control device. Preferably, the electro-magnetic coupling maybe formed as a friction clutch.

The electrical control device is constituted of the following elements,considered, in the direction of its operating sequence towards thecontrol valve, of a first voltage supply having a voltage proportionedin correspondence with the engine speed, and which may include atachometer generator; a second voltage supply independent of the firstvoltage and which is set so as to be proportional with a desired presetengine speed value, an electronic comparator receiving the first andsecond voltages and having an output voltage formed by the differentialbetween the first and second voltages, an electric amplifier connectedto the comparator output, and a variable-speed electric motor connectedto the amplifier output and including a number of selectivelyswitched-in drives connected to the output shaft of the motor.

The first voltage, which is proportional to the engine speed, may alsobe generated with the assistance of a suitable impulse counter andenergy conversion device, which is provided by the impulses of theengine ignition interruptors, or may be synchronous with an inductivemember such as an induction coil extending about the engine crankshaft.

The electrical control device includes at least one integrally operatingcontrol or behavioral pattern. Further, during selective operatingmodes, the electrical control device may also include a proportionallyor differentially operating control or behavioral pattern. Thevariable-speed electric motor preferably includes a practicallyinstantaneously operating airbrake installation which, in a currentlesscondition, brakes the motor to a full stop. In lieu thereof, thevariable speed motor may incorporate a stepping-switch arrangement. Asuitable crankshaft drive, including a plate cam-and followerarrangement, is located between the electromagnetic coupling and thecontrol valve.

It is accordingly an object of the present invention to provide animproved and novel speed regulator for an internal combustion engine soas to afford the engine increased applications for driving alternatingcurrent and three-phase current generators having a constant phasefrequency.

Another object of the present invention is to provide a speed regulatoror control device for an internal combustion engine adapted to maintainthe engine at constant speeds under variable engine loads acting overextensive operating ranges.

Still another object of the present invention is to provide for a speedcontrol device for an internal combustion engine which becomes operativeonly upon the engine attaining a predetermined minimum operatingtemperature.

A further object of the present invention is to provide for a speedregulator or control device for an internal combustion engine whichincorporates an electrical switching system adapted, upon interruptionof an electrical current being supplied to the'control device, to

position the control valve so as to convey a flow of fuelair mixtureinto the engine at a rate corresponding to the engine idling mode.

A BRIEF DESCRIPTION OF THE DRAWINGS Reference may now be had to thedrawings, describing a preferred embodiment of the invention, in which:

FIG. 1 illustrates a partially schematic view of a speed control deviceand control valve arrangement for an internal combustion engine inaccordance with the present invention; and

FIG. 2 shows a view in the direction of arrow A in FIG. 1, illustratingthe control valve, including the return spring, cam plate and followerarrangement of the camshaft drive of the internal combustion engine.

DETAILED DESCRIPTION Referring now in detail to the drawings, an enginespeed regulator assembly includes a tachometer generator 11, the latterof which is connected to a I crankshaft assembly 23 of an internalcombustion engine (not shown).

The tachometer generator 11 is connected to the input of a regulator 12,and generates a voltage which is proportionate to the rate of speed ofthe'internal combustion engine, the voltage being supplied to the inputof the, regulator 12 in a controlled intensity X. A potentiometer 13provides a variable voltage which is designated as the drive potentialvoltage intensity W, and is similarly connected into another input ofthe reg ulator 12. The regulator 12 contains a standard type ofelectronic comparator 40 which may be simply designated by an electricalbridge connection 41 and a transistor 42. Y

The differential between the two input voltages X and W fed intoregulator 12 provides a voltage output intensity Y, which is conductedto and amplified in an amplifier 14, and then further conducted to avariablespeed electric motor 15. In accordance with the polarity of theoutput current, and output shaft 16 of the electric motor may be rotatedclockwise or counterclockwise.

A brake 17 is adapted to be actuated so as to provide a braking effecton output shaft 16. The brake 17 is adapted to be actuated or raisedaway from contact with shaft 16 by means of air'operated magnets 18. Themagnets 18 are actuated through an independent electrical power supplycircuit 19, which may be closed by means of a voltage relay 20. As soonas a voltage is generated at theoutput end of the amplifier 14, theairoperated magnets 18 are released and the brake 17 is moved away fromshaft 16 so as to permit the latter to rotate.

A drive 21 connects the electric motor 15 to a control valve 22 whichmay controllably set through a variation of The connection provided bythe drive 21 also incorporates a crankshaft assembly or drive 23 whichincludes a cam plate 24 connected to a shaft 28. An eccentric 26,including a follower roller 27, is fastened to an end of a control valveshaft 25. The shaft 28 is connected to an output shaft 30 of drive 21through a shaft coupling 29. The coupling 29 includes electrical circuit31 actuating coupling magnets 32 which may be closed through theoperation of a thermal switch 33. Upon the temperature of the internalcombustion engine reaching a predetermined minimum operating value, thethermal switch 33, which may be located in the cooling system of theinternal combustion engine, closes the electrical circuit 31 so as toprovide electro-magnetic coupling of shafts 30 and 28 whereby the twoshafts are driven in unison. The thermal switch 33 will prevent therotational speed of the internal combustion engine, upon cold startingunder load conditions, approaching drive speed since at that time asufficiently rich fuel-air mixture for satisfactory engine operation isnot readily available.

The opposite end of control valve shaft 25 includes a stub shaft 34,having one end of the lever 35 fastened thereto. The other end of lever35 is connected to a tensioned return spring36, as shown in FIG. 2 ofthe drawing, which imparts a tensile force to the control valve 22tending to pull the latter into a fuel-air mixture flow rate attitudecorresponding to the engine idling mode.

Upon cold starting of the internal combustion engine, a voltage isprovided through an auxiliary contact, concurrent with the switching inof the engine ignition, in electrical circuits 19 and 31, and in theelectrical circuit 'of the amplifier 14. The coupling 29 between shafts28 and 30 remains open and the spring 36 restrains control valve 22 inthe engine idling mode, as shown in FIG. 2 of the drawing. After enginestarting,

the internal combustion engine runs at an idling speed,

which is below the loaded operating speed of the engine. Since thetachometer generator 11 provides a voltage which is proportional to theengine idling speed, regulator 12 provides output voltage intensity Ycorresponding to the difference between the voltage intensity W providedby potentiometer 30 and the voltage intensity X generated by thetachometer generator. Amplifier 14 increases the value of voltageintensity Y to a height or intensity sufficient for the operation ofvariable-speed electric motor 15. Concurrently, voltage relay 20 isexcited by a voltage generated across a conductor 37, thereby openingclosed electrical circuit 19. This causes the air-operated magnets 18 torelease brake 17, allowing rotation of shaft 16 and drive 21 so as todrive output shaft 30 in response thereto.

During this time internal, shaft coupling 29 is open, and remains inthat position until thermal switch 33 senses that a predeterminedminimum operating temperature for the internal combustion engine hasbeen reached. At that instant, electrical circuit 31 is opened andcoupling magnets 32 allows coupling 29 to interconnect shafts 28 and 30.The coupling of the shafts is obtained in a generally smoothtransitional sequence, since the coupling is preferably formed as afriction clutch.

Upon shafts 28 and 30 being coupled, cam plate 24 is rotated in eitherdirection, depending upon the polarity of the current, by electric motor15, as shown in FIG. 2, and concurrently displaces eccentric 26 throughfollower roller 27 so as to pivot the control valve shaft 25 includingcontrol valve 22 in opposition to the tensile force of the spring 36into an opening relationship until current ceases to flow throughelectric motor 15, in effect, until the measured engine speed coincideswith the preset engine speed value on potentiometer 13. The increase inthe engine speed is thereby facilitated, since an increased flowcrosssection is provided through control valve 22 for an increased flowof combustion air, such as fuel-air mixture, into the internalcombustion engine.

The variation in the cross-sectional flow aperture through the controlvalve 22 is not proportionate to the angle or degree of the valveopening extent. Accordingly, by an appropriate configuration of platecam 24 it is possible that the flow-through cross-section of controlvalve 22 may be controlled so as to be approximately directlyproportional to the rotational angle of shaft 28. In other embodimentsthe shape of the cam plate may be modified so as to provide furthervalve proportioning, and through experimentation based on the particularfield of application adapted to the requirements of the associatedinternal combustion engine.

The selection of regulator 12 and of the variablespeed electric motordetermines the control or behavioral pattern of the entire speed controldevice. An integrally controlled pattern or behavioral mode is presentedwhen the motor receives a constant voltage from the regulator whichforms the voltage output intensity, as long as a speed control deviationis in evidence. This will cause the control valve 22 to be varied aslong as or until the deviation of the control voltage drops to zero. Inactual operation, various fluctuations deviating from the preset enginespeed value are experienced, which may be controlled within permissibleparameters for lengthy periods of time through suitable controlprocedures.

A control or behavioral pattern of a greatly increased variable outputis presented when electrical motor 15 consists of, for example,-adirect-current motor and receives at a predetermined intensity an outputvoltage from regulator 12, which is proportional to the voltage based onthe degree of control deviation. This provides a control velocity whichis increased in direct proportion to the increase of the instantaneouscontrol deviation. The speed control thereby becomes quite rapid and isdecreased to lesser and lesser amount as the control deviation becomessmaller. In accordance with a predetermined minimum valve of the controldeviation, extending down to the value zero, the electric motor 15receives a constant voltage. This, for example, occurs by providing amono-stable switching arrangement in the form of a Schmitt triggerswitch connected in parallel with a known preset speed value comparisonswitching arrangement in regulator 12.

At the commencement of engine speed control, the proportional behavioralmode dominates, whereas at the end of the speed control the integralpattern dominates. The remaining control deviation accordingly is thenzero, in accordance with a purely integrally functioning controlrelationship. This type of control may be better measured with regard toengine drive conditions.

Finally, in the intermediate control range, a proportional controlpattern may be directly provided, for example, by forming one of thebridge resistances in regulator 12 as a proportionate member. Thisfacilitates the high speed operation of the internal combustion engineeven more rapidly than by an exclusively intergrally controlledbehavioral mode or pattern. However, in this instance, at the first passthrough zero, larger deviations from preset speed values may beencountered than in the other embodiments.

In order to effect the control over the engine speed, it is importantthat the electric motor 15 be instantly braked as soon as the presetengine speed value is attained. In order to achieve this purpose, brake17 may be provided with a step-switch system in lieu of airoperatedmagnet 18, for example, a Maltese drive may be provided. Furthermore,the electric motor 15 itself may consist of a step-motor. Similarly, thelow-voltage relay 20 may be constituted as a time relay.

Upon interruption of the electrical power supply to the control device,or upon shutting-off of the ignition of the internal combustion engine,electrical current flow to coupling magnet 32 is discontinued.Accordingly, since shaft coupling 29 is thereby released so as todisengage the shafts 28 and 30, return spring 36 pulls control valve 22into an engine idling mode or attitude.

This operative sequence is incorporated for reasons of engine safety.The foregoing operative sequence prevents the internal combustion enginefrom exceeding its allowable speed upon interruption of the power supplyto the control device, and concurrently provides for a controlled speedincrease from the idling speed ofthe engine.

The advantages obtained by the present invention, in

essence, particularly provide for in that control over the engine speedis first initiated when the internal combustion engine reaches apredetermined iminimum operating temperature, and upon interruption ordisturbance of the control device voltage, the control valve isautomatically moved into an engine idling attitude. This also willprevent, through use of the foregoing, speed control disturbances, andif these do occur, the disturbances are rendered harmless to the engine.

A further advantage of the invention lies in the rapid and broadlyeffective constant and fluctuation-free engine speed control, which isachieved by the speed control behavioral modes or patterns in aninventive combination of integral and proportional, or proportional, orintegral and differential control patterns.

While there has been shown what is considered to be the preferredembodiment of the invention, it will be obvious that modifications maybe made which come within the scope of the disclosure and of theappended claims.

I claim:

1. In a speed regulator for an internal combustion engine having acontrol valve for regulating the flow of a fuel-air mixture to saidengine; an electrical control device connected to said control valve,said control device including means for continuously measuring the speedof the engine, means for comparing the measured engine speed with apreset speed value, and means for adjusting the flow setting of saidcontrol valve in accordance with the measured differential between theengine speed and the preset speed value, the

tioned in the circuit of said electrical control device,

said switch means being adapted to interrupt connection between saidcontrol device and said control valve until saidengine attains apredetermined minimum operating temperature; means for setting said.control valve to provide a flow of said fuel-air mixture in an engineidling mode during the period of interrupted connection between thecontrol device and the control valve; a variable-speed electric motorconnected to said control valve; a low-voltage relay interposed in anelectrical line energizing said motor, said electric motor includingsubstantially instantaneously actuatable, electrically-controlled airbrake means, said air brake means braking said motor in response tointerruption to the flow of electrical current thereto and being adaptedto receive an actuating brake-releasing current'coincident withresumption of current flow through said motor, said low-voltage relaybeing responsive to variations in the electrical current being appliedto said electrical control device whereby, upon interruption of theelectrical current to said control device, said motor adjusts thesetting of said control valve into the engine idling mode.

2. An improvement as claimed in claim 1, the connection between theelectrical control device and said with said control valve for movingthelatter into an engine idling mode upon said current interruption.

3. An improvement as claimed in claim 2, wherein said electromagneticcoupling comprises a friction clutch.

4. An improvement as claimed in claim 1, wherein the connection betweensaid electrical control device and said control valve comprises a firstvoltage source,

means for varying the intensity of said voltage in proportion to thespeed of said engine; a second voltage source independent of said firstvoltage source, said second voltage being adjustable in proportion tothe preset speed value of said engine, said comparing means comprisingan electronic comparator having an output voltage corresponding to thedifference between said first and second voltages; an electricalamplifier receiving said output voltage; and a variablespeed electricmotor.

5. An improvement as claimed in claim 4, said intensity varying meansfor said first voltage comprising a tachometer-generator.

6. An improvement as claimed in claim 2, comprising crankshaft drivemeans disposed intermediate said electromagnetic coupling and saidcontrol valve.

7. An improvement as claimed in claim 6, said crankshaft drive meansincluding a plate cam and cam follower arrangement.

8. An improvement as claimed in claim 1, said control valve comprising apivotable disc valve disposed in a fuel-air mixture supply conduit ofsaid engine.

1. In a speed regulator for an internal combustion engine having acontrol valve for regulating the flow of a fuel-air mixture to saidengine; an electrical control device connected to said control valve,said control device including means for continuously measuring the speedof the engine, means for comparing the measured engine speed with apreset speed value, and means for adjusting the flow setting of saidcontrol valve in accordance with the measured differential between theengine speed and the preset speed value, the improvement comprising;thermal switch means responsive to the temperature of the engine beingpositioned in the circuit of said electrical control device, said switchmeans being adapted to interrupt connection between said control deviceand said control valve until said engine attains a predetermined minimumoperating temperature; means for setting said control valve to provide aflow of said fuel-air mixture in an engine idling mode during the periodof interrupted connection between the control device and the controlvalve; a variable-speed electric motor connected to said control valve;a low-voltage relay interposed in an electrical line energizing saidmotor, said electric motor including substantially instantaneouslyactuatable, electrically-controlled air brake means, said air brakemeans braking said motor in response to interruption to the flow ofelectrical current thereto and being adapted to receive an actuatingbrake-releasing current coincident with resumption of current flowthrough said motor, said low-voltage relay being responsive tovariations in the electrical current being applied to said electricalcontrol device whereby, upon interruption of the electrical current tosaid control device, said motor adjusts the setting of said controlvalve into the engine idling mode.
 2. An improvement as claimed in claim1, the connection between the electrical control device and said controlvalve comprising an electromagnetic coupling, said coupling beingadapted to interrupt connection between said control device and saidvalve in response to an interruption of the electrical current supply tosaid control device; and tension spring means associated with saidcontrol valve for moving the latter into an engine idling mode upon saidcurrent interruption.
 3. An improvement as claimed in claim 2, whereinsaid electromagnetic coupling comprises a friction clutch.
 4. Animprovement as claimed in claim 1, wherein the connection between saidelectrical control device and said control valve comprises a firstvoltage source, means for varying the intensity of said voltage inproportion to the speed of said engine; a second voltage sourceindependent of said first voltage source, said second voltage beingadjustable in proportion to the preset speed value of said engine, saidcomparing means comprising an electronic comparator having an outputvoltage corresponding to the difference between said first and secondvoltages; an electrical amplifier receiving said output voltage; and avariable-speed electric motor.
 5. An improvement as claimed in claim 4,said intensity varying means for said first voltage comprising atachometer-generator.
 6. An improvement as claimed in claim 2,comprising crankshaft drive means disposed intermediate saidelectromagnetic coupling and said control valve.
 7. An improvement asclaimed in claim 6, said crankshaft drive means including a plate camand cam follower arrangement.
 8. An improvement as claimed in claim 1,said control valve comprising a pivotable disc valve disposed in afuel-air mixture supply conduit of said engine.